Manganese Silylene Hydride Complexes: Synthesis and Reactivity with Ethylene to Afford Silene Hydride Complexes.

Abstract

Reaction of the ethylene hydride complex trans-[(dmpe)2 MnH(C2 H4 )] (1) with Et2 SiH2 at 20 °C afforded the silylene hydride [(dmpe)2 MnH(=SiEt2 )] (2 a) as the trans-isomer. By contrast, reaction of 1 with Ph2 SiH2 at 60 °C afforded [(dmpe)2 MnH(=SiPh2 )] (2 b) as a mixture of the cis (major) and trans (minor) isomers, featuring a Mn-H-Si interaction in the former. The reaction to form 2 b also yielded [(dmpe)2 MnH2 (SiHPh2 )] (3 b); [(dmpe)2 MnH2 (SiHR2 )] (R=Et (3 a) and Ph (3 b)) were accessed cleanly by reaction of 2 a and 2 b with H2 , and the analogous reactions with D2 afforded [(dmpe)2 MnD2 (SiHR2 )] exclusively. Both 2 a and 2 b engaged in unique reactivity with ethylene, generating the silene hydride complexes cis-[(dmpe)2 MnH(R2 Si=CHMe)] (R=Et (4 a), Ph (4 b)). Compounds trans-2 a, cis-2 b, 3 b, and 4 b were crystallographically characterized, and bonding in 2 a, 2 b, 4 a, and 4 b was probed computationally.